This is a great question. I am currently summarizing WindyTY forecasts for a fellow sailor who is in the South Pacific by satellite email. He has only sporadic internet connection, so being able to dump WindyTY data into a offline app would be fantastic.

Correct. I've been attempting to use other Leaflet API code that I have from previous projects. A lot of the setup for this seems to be taken care of within the windytv api making it a bit difficult to slice the map how I would like.

@meteo-GR Yes, FL makes sense. We will consider it.
I made some investigation about how the ECMWF freezing level is computed, when there are multiple "zero-degree levels" in one point, so for your information I post description here:
Freezing altitude shows height of the point where temperature goes from positive to negative values when scanning values from surface upwards. When there are multiple such points, then the second point (from surface) is displayed. Effect of this approach is that when there is inversion, then the "zero-crossing" above the inversion is shown.

@johnf13 BOM is definitely right. As I wrote, it is difficult to forecast peak values. You should not use medium range mathematical model to determine exact peak value. But if you want information of cyclone future movement, if you want good prediction for 1-3 days, look at model forecasts. And if you want easy-to-use presentation of such model forecasts, use Windytv.